Recently, contactless power transmission technology for transmitting power from a power feeding side to a power receiving side contactlessly is attracting attention. For example, in the power transmission by using magnetic field, the power is transmitted from the coil of the transmission side to the coil of the power receiving side via the magnetic field generated by the coil of the transmission side. A part of the magnetic field generated by the coil of the transmission side will be leaked during the power transmission by using magnetic field, and the leaked magnetic field will cause various problems.
As one of the problems, generation of an induced current caused by the leaked magnetic field can be listed. In Patent Document 1 and Patent Document 2, a problem is described that in the contactless power feeding device for supplying power to a movable body such as an electric vehicle or the like contactlessly, an induced current flows into an iron plate used in the floor of the vehicle body equipped with an power receiving part, and thus the iron plate generates heat. Moreover, it is disclosed that in order to prevent the induced current from generating, an aluminum plate is disposed on the back surface of the power receiving part. In addition, a problem also arises that the efficiency of the contactless power feeding device reduces due to the power loss caused by the induced current.
In the contactless power feeding device disclosed in Patent Document 1 and Patent Document 2, power is transmitted in a vertical direction from the power transmission part horizontally disposed on the ground to the power receiving part disposed under the floor of the vehicle body. Thus, a countermeasure against the leaked magnetic field in a supposed horizontal power transmission is not studied in Patent Document 1 and Patent Document 2. That is, the effect of the leaked magnetic field in a direction of the ground is not studied because it is supposed that the power is transmitted in a vertical direction.